Difference between revisions of "Functions composed of Physical Expressions"

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(Lorentz Force for (q,q'))
(Lorentz Force for (q,q'))
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The Lorentz Force can be expressed directly in terms of the potentials:
 
The Lorentz Force can be expressed directly in terms of the potentials:
  
:<math>\mathbf{F} = q\left[- \nabla \varphi - \frac{∂\mathbf{A}}{∂t} + \mathbf{v} \left( \nabla \times \mathbf{A} \right)\right]</math>
+
:<math>\mathbf{F} = q\left[- \nabla \varphi - \frac{∂\mathbf{A}}{∂t} + \mathbf{v} \times \left( \nabla \times \mathbf{A} \right)\right]</math>
  
 
Where:
 
Where:
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* <math>-\nabla \varphi</math> = negative the gradient of the scalar potential <math>\varphi</math>.
 
* <math>-\nabla \varphi</math> = negative the gradient of the scalar potential <math>\varphi</math>.
 
* <math>-\frac{∂\mathbf{A}}{∂t}</math> = negative the partial derivative of the magnetic vector potential <math>\mathbf{A}</math> with respect to time <math>t</math>.
 
* <math>-\frac{∂\mathbf{A}}{∂t}</math> = negative the partial derivative of the magnetic vector potential <math>\mathbf{A}</math> with respect to time <math>t</math>.
* <math>\mathbf{v} \left( \nabla \times \mathbf{A} \right)</math> = the cross product of the velocity <math>\mathbf{v}</math> of the charge <math>q</math> and the curl of the magnetic vector potential <math>\nabla \times \mathbf{A} = \mathbf{B}</math> due to charge <math>q'</math>.
+
* <math>\mathbf{v} \times \left( \nabla \times \mathbf{A} \right)</math> = the cross product of the velocity <math>\mathbf{v}</math> of the charge <math>q</math> and the curl of the magnetic vector potential <math>\nabla \times \mathbf{A} = \mathbf{B}</math> due to charge <math>q'</math>.
  
 
To restate from a previous section, the magnetic vector potential of a charge <math>q</math> experienced by a charge <math>q</math> is:
 
To restate from a previous section, the magnetic vector potential of a charge <math>q</math> experienced by a charge <math>q</math> is:
  
<math>\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right) =  \underset{constant}{\frac{\mu_0\ q'}{4\pi}} \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}} \underset{dislocation}{\frac{d\mathbf{r'}}{dt}}</math>
+
<math>\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right) =  \underset{constant}{\frac{\mu_0\ q'}{4\pi}} \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}} \underset{dislocation}{\frac{\mathbf{r'}}{∂t}}</math>
  
 
The partial derivative of this with respect to time <math>t</math> is:
 
The partial derivative of this with respect to time <math>t</math> is:
  
<math>\frac{∂\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right)}{∂t} = \underset{constant}{\frac{\mu_0\ q'}{4\pi}} + \underset{proximity}{ \frac{ ∂\left[ \frac{1}{|\mathbf{r}-\mathbf{r'}|} \right] }{∂t}} \underset{dislocation}{\frac{d\mathbf{r'}}{dt}} + \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}} \underset{dislocation}{ \frac{ ∂\left[ \frac{d\mathbf{r'}}{dt} \right] }{∂t}}</math>
+
<math>\frac{∂\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right)}{∂t} = \underset{constant}{\frac{\mu_0\ q'}{4\pi}} \left[ \underset{proximity}{ \frac{ ∂\left[ \frac{1}{|\mathbf{r}-\mathbf{r'}|} \right] }{∂t}} \underset{dislocation}{\frac{\mathbf{r'}}{∂t}} + \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}} \underset{dislocation}{ \frac{ ∂\left[ \frac{\mathbf{r'}}{∂t} \right] }{∂t}} \right]</math>
  
 
==See also==
 
==See also==

Revision as of 00:40, 15 May 2016

Functions for a point charge [math]q'[/math]

The electric scalar potential [math]\mathbf{\varphi}[/math] at [math]\left(\mathbf{r},t\right)[/math] due to a point charge [math]q'[/math] at [math]\left(\mathbf{r'},t'\right)[/math] is:

[math]\mathbf{\varphi}\left(\mathbf{r},\mathbf{r'}\right) = \underset{constant}{\frac{q'}{4\pi\ \epsilon_0}} \times \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}}[/math]

The magnetic vector potential [math]A[/math] at [math]\left(\mathbf{r},t\right)[/math] due to a point charge [math]q'[/math] which had a velocity [math]\frac{d\mathbf{r'}}{dt}[/math] at [math]\left(\mathbf{r'},t'\right)[/math] is:

[math]\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right) = \mathbf{\varphi}\left(\mathbf{r},\mathbf{r'}\right) \times \underset{constant}{\frac{1}{c^2}} \times \underset{dislocation}{\frac{d\mathbf{r'}}{dt}}[/math]

[math]\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right) = \underset{constant}{\frac{\mu_0\ q'}{4\pi}} \times \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}} \times \underset{dislocation}{\frac{d\mathbf{r'}}{dt}}[/math]

Functions for an ordered pair of point charges [math](q,q')[/math]

A charge [math]q[/math] subject to an electric scalar potential [math]\varphi[/math] at [math]\left(\mathbf{r},t\right)[/math] due to a point charge [math]q'[/math] at [math]\left(\mathbf{r'},t'\right)[/math] has an electric potential energy of:

[math]q\varphi\left(\mathbf{r},\mathbf{r'}\right) = \underset{constant}{\frac{qq'}{4\pi\ \epsilon_0}} \times \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}}[/math]

A charge [math]q[/math] subject to a magnetic vector potential [math]A[/math] at [math]\left(\mathbf{r},t\right)[/math] due to a point charge [math]q'[/math] which had a velocity [math]\frac{d\mathbf{r'}}{dt}[/math] at [math]\left(\mathbf{r'},t'\right)[/math] has a potential momentum of:

[math]q\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right) = \varphi\left(\mathbf{r},\mathbf{r'}\right) \times \underset{constant}{\frac{q}{c^2}} \times \underset{dislocation}{\frac{d\mathbf{r'}}{dt}}[/math]
[math]q\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right) = \underset{constant}{\frac{\mu_0\ qq'}{4\pi}} \times \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}} \times \underset{dislocation}{\frac{d\mathbf{r'}}{dt}}[/math]

Lorentz Force for [math](q,q')[/math]

The Lorentz Force between charges [math](q,q')[/math] can be derived from the scalar potential [math]\varphi[/math] and the vector potential [math]\mathbf{A}[/math].

A charge [math]q[/math] which has a velocity of [math]\mathbf{v}[/math] at [math]\left(\mathbf{r},t\right)[/math] will experience a Lorentz force due to a point charge [math]q'[/math] at [math]\left(\mathbf{r'},t'\right)[/math] of:

[math]\mathbf{F} = q\left[\mathbf{E} + \mathbf{v} \times \mathbf{B}\right][/math]

The electric field [math]\mathbf{E}[/math] is:

[math]\mathbf{E} = - \nabla \varphi - \frac{∂\mathbf{A}}{∂t}[/math]

The magnetic field [math]\mathbf{B}[/math] is:

[math]\mathbf{B} = \nabla \times \mathbf{A}[/math]

The Lorentz Force can be expressed directly in terms of the potentials:

[math]\mathbf{F} = q\left[- \nabla \varphi - \frac{∂\mathbf{A}}{∂t} + \mathbf{v} \times \left( \nabla \times \mathbf{A} \right)\right][/math]

Where:

  • [math]-\nabla \varphi[/math] = negative the gradient of the scalar potential [math]\varphi[/math].
  • [math]-\frac{∂\mathbf{A}}{∂t}[/math] = negative the partial derivative of the magnetic vector potential [math]\mathbf{A}[/math] with respect to time [math]t[/math].
  • [math]\mathbf{v} \times \left( \nabla \times \mathbf{A} \right)[/math] = the cross product of the velocity [math]\mathbf{v}[/math] of the charge [math]q[/math] and the curl of the magnetic vector potential [math]\nabla \times \mathbf{A} = \mathbf{B}[/math] due to charge [math]q'[/math].

To restate from a previous section, the magnetic vector potential of a charge [math]q[/math] experienced by a charge [math]q[/math] is:

[math]\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right) = \underset{constant}{\frac{\mu_0\ q'}{4\pi}} \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}} \underset{dislocation}{\frac{∂\mathbf{r'}}{∂t}}[/math]

The partial derivative of this with respect to time [math]t[/math] is:

[math]\frac{∂\mathbf{A}\left(\mathbf{r},\mathbf{r'}\right)}{∂t} = \underset{constant}{\frac{\mu_0\ q'}{4\pi}} \left[ \underset{proximity}{ \frac{ ∂\left[ \frac{1}{|\mathbf{r}-\mathbf{r'}|} \right] }{∂t}} \underset{dislocation}{\frac{∂\mathbf{r'}}{∂t}} + \underset{proximity}{\frac{1}{|\mathbf{r}-\mathbf{r'}|}} \underset{dislocation}{ \frac{ ∂\left[ \frac{∂\mathbf{r'}}{∂t} \right] }{∂t}} \right][/math]

See also

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